A review of 1,069 total admissions of 537 systemic lupus erythematosus (SLE) patients during a 10-yr period at Ramathibodi Hospital showed that 220 episodes which occurred in 137 patients (25.5%) were motivated by infection. Skin was the most common site (23%) with Herpes zoster being the most common organism (15.5%) found in our lupus patients. However, if we considered only major infections, pulmonary tuberculosis, salmonella septicemia and urinary tract infection by E. coli would be the most frequent complications respectively. In the absence of immunosuppressive therapy, infections coincided with the initial manifestation of SLE in 25 patients and were associated with exacerbation of the disease in 20 patients. Mean SLEDAI score in these patients was 8.8, suggesting that active lupus link together with infection. Steroid therapy influenced the rate of opportunistic infections (p = 0.006). Infections were determined to be the cause of death in 23 of 77 patients (29.9%). Opportunistic pathogens played an equal role as other common bacterial organisms in these fatal cases. SLE patients who died from infections were treated with cyclophosphamide in higher proportion than those with no infectious complication (p = 0.025). Our study demonstrated the rate, nature and predisposing factors of infection in SLE which may lead to better anticipation and diminution of morbidity and mortality related to infection in hospitalized patients with SLE.